Something weird happened to me.
I figured out how to encrypt/decrypt. Except when I try to decrypt it, only one of the characters is off by 1.
Before I looked over my work, I just changed that one character to see if it gave me the right encryption, and it did. But when I look over my work, I see no error that could have caused that single character to be off by one. I don't know if its just some stupid thing I looked over, but I want to learn as much as possible from these challenges, so I really want to know how I was off by one value on only one of the characters.
Nevermind actually, I figured it out... I had just copied the original ciphertext wrong. If anybody has the same issue, I recommend checking that. Nice challenge though, as for people who are having trouble figuring it out, I recommend encrypting a bunch of simple 5 character strings and trying to reverse engineer them. (e.g. type "aaaaa" into it and see what you get)